Well, if he just leaves this running, assuming the same level of profitability it is 17k a year of passive income...definitely worth keeping up if possible. as the exchange rate goes up it should become even more profitable.
I was only able to run 60 nodes for the first two days. After that, spot market prices in CA and Oregon went too high for profitability.
At this point, the spot market has gone insane. Mining with my code isn't profitable over about $0.130/hour with the current exchange rates, and the market is at, um, $6/hour in some places. I hypothesize that people are typo'ing in their EC2 spot bids and typing $6 when they mean $0.6, because otherwise it's completely irrational: You can get a normal instance for $0.65/hour. Not that people are rational, but...
It also requires some care and feeding. The $17k isn't really free passive income. The pools go awry, the exchanges go awry, ... At larger scale, you could amortize all of that management time and automate the majority of it, but at a few bucks here and there it's simply not worth it.
Maybe OP could automatically run his miners when such situations arrive, but I think it's unlikely to net anything like $17k/yr.
Edit: sliverstorm described this way better than I could.
Much like with most forms of arbitrage, and exploitable patterns in the stock market. You discovery the opportunity, you make a little $$, and the hole quickly closes as everyone else capitalizes on it too.